Ok, given the formula for figuring the second half of an Aikido circuit could a #26 Aikido be made? Anyone that has played with a #26 tube can tell you of the hum associated with it and the need for a battery heater supply.
Would the Aikido circuit therefore be capable of nulling the hum factor without using the battery and charger setup?
Wouldn't this make a nice diy project?
Would the Aikido circuit therefore be capable of nulling the hum factor without using the battery and charger setup?
Wouldn't this make a nice diy project?
check out my article on a 26 transformer coupled pre-amp at Positive Feedback online or go to my website where you will see most of the sameinformation..
http://www.kta-hifi.net/
The problems you are likely to have with the 26 revolve around its high microphony, doing good 1.5V dc filaments supplies is relatively easy.
Transformer coupling works very well with this type and because of the low overall gain mechanical disturbances are not amplified as much as would be the case for RC coupled designs.
I would seriously recommend anyone using these or the 01A mount them on a mechanically isolated (soft rubber bushings) subchassis in their pre-amp design.
Note that they are also quite sensitive to external electrostatic fields and benefit from shielding. (I use cheap copper foil cans around mine.)
Kevin
http://www.kta-hifi.net/
The problems you are likely to have with the 26 revolve around its high microphony, doing good 1.5V dc filaments supplies is relatively easy.
Transformer coupling works very well with this type and because of the low overall gain mechanical disturbances are not amplified as much as would be the case for RC coupled designs.
I would seriously recommend anyone using these or the 01A mount them on a mechanically isolated (soft rubber bushings) subchassis in their pre-amp design.
Note that they are also quite sensitive to external electrostatic fields and benefit from shielding. (I use cheap copper foil cans around mine.)
Kevin
Anyone that has played with a #26 tube can tell you of the hum associated with it and the need for a battery heater supply.>
Well, I thought that until I connected one side of my balanced 26 line stage to SLA batteries and the other side to a Thurlby Thandar PL154 bench power supply (0-15v, 4A). On my system hum was practically non existant on the bench supply and the sound quality was virtually identical. My speakers are Monacor SPH-130AL single aluminium 5" drivers, sensitivity listed at 88db. the line stage handles the output from my DAC digital board.
So, in these circumstances, I feel confident you could use a well filtered DC supply. My line stage is balanced - no idea if that lowers hum but I doubt it. There is a very low level of hum, by which I mean barely audible with your ear against the cone. Whether this would be a worry on a high efficiency horn I can't say. No hum on the batteries. Andy
Well, I thought that until I connected one side of my balanced 26 line stage to SLA batteries and the other side to a Thurlby Thandar PL154 bench power supply (0-15v, 4A). On my system hum was practically non existant on the bench supply and the sound quality was virtually identical. My speakers are Monacor SPH-130AL single aluminium 5" drivers, sensitivity listed at 88db. the line stage handles the output from my DAC digital board.
So, in these circumstances, I feel confident you could use a well filtered DC supply. My line stage is balanced - no idea if that lowers hum but I doubt it. There is a very low level of hum, by which I mean barely audible with your ear against the cone. Whether this would be a worry on a high efficiency horn I can't say. No hum on the batteries. Andy
Gee, I must be doing something all wrong. Even with a battery I was unable to get rid of the hum. The hum was there if I used a regulated supply or battery. There is a chance I may be hearing more noise because my speakers are in excess of 100db 1w 1m.
Even with over 100,000 mfd of cap I still had hum so I gave up on it.
Even with over 100,000 mfd of cap I still had hum so I gave up on it.
http://home.pacifier.com/~gpimm/battery charger.gif
This is an example of someone elses need for the battery charger and battery setup when trying to tame the #26 hum problem.
This is an example of someone elses need for the battery charger and battery setup when trying to tame the #26 hum problem.
are you into horns? I like them, if only I could afford some...
My speaker system is the old JBL Rhodes C37 cabinet with 075 horn tweeter and D130 15" woofer. The Rhodes cabinet is a reflex design, overall efficiency is well over 100dB, no audible hum from the pre-amp with my 300B se amplifier which has around 22dB of gain.
You can definitely get quiet out of a 26, putting an electrostatic shield around it may help.. You can make one to try out of tin foil.. LOL
edit: fix my usual stupid typos
You can definitely get quiet out of a 26, putting an electrostatic shield around it may help.. You can make one to try out of tin foil.. LOL
edit: fix my usual stupid typos
Howdy,
There are alot of different approaches you can take, but I would recommend transformer coupling because the 26 has an RP of about 8K which is pretty high and runs at a relatively high plate current.
(I'm running at around 6mA.)
Lots of other people make line transformers, what you need is an SE 15K to 600 ohms rated for about 8mA. Try the usual suspects; magnequest, electraprint or edcorusa - all of which would make what you need. I suspect the edcor might be the most cost effective and from what I have heard they actually make pretty good transformers.
(I'm going to try some for another 45 amplifier soon.)
Kevin
There are alot of different approaches you can take, but I would recommend transformer coupling because the 26 has an RP of about 8K which is pretty high and runs at a relatively high plate current.
(I'm running at around 6mA.)
Lots of other people make line transformers, what you need is an SE 15K to 600 ohms rated for about 8mA. Try the usual suspects; magnequest, electraprint or edcorusa - all of which would make what you need. I suspect the edcor might be the most cost effective and from what I have heard they actually make pretty good transformers.
(I'm going to try some for another 45 amplifier soon.)
Kevin
I don't have the full specs to hand for the HA-133, but I can tell you that the primary Z is 15K and the secondary is 600 or 150 ohms.
There are two primary windings, and two secondaries.
Max primary current is about 8mA, however I run them at 6mA where I think they sound better.
The HA-133 is pretty rare and expensive, however Magnequest makes some very good sounding 15K plate to line transformers.
There are two primary windings, and two secondaries.
Max primary current is about 8mA, however I run them at 6mA where I think they sound better.
The HA-133 is pretty rare and expensive, however Magnequest makes some very good sounding 15K plate to line transformers.
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